linux-kernel - Re: [RFC RESEND v10 03/14] irq & spin_lock: Add counted interrupt disabling/enabling

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Message-ID: <aFBcTePC-iXqRuXq@Mac.home>
Date: Mon, 16 Jun 2025 11:02:53 -0700
From: Boqun Feng <boqun.feng@...il.com>
To: Joel Fernandes <joelagnelf@...dia.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Lyude Paul <lyude@...hat.com>,
	rust-for-linux@...r.kernel.org,	Thomas Gleixner <tglx@...utronix.de>,
 linux-kernel@...r.kernel.org,
	Daniel Almeida <daniel.almeida@...labora.com>,
	Ingo Molnar <mingo@...hat.com>, Juri Lelli <juri.lelli@...hat.com>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Steven Rostedt <rostedt@...dmis.org>,	Ben Segall <bsegall@...gle.com>,
 Mel Gorman <mgorman@...e.de>,	Valentin Schneider <vschneid@...hat.com>,
	Will Deacon <will@...nel.org>, Waiman Long <longman@...hat.com>,
	Miguel Ojeda <ojeda@...nel.org>,	Alex Gaynor <alex.gaynor@...il.com>,
 Gary Guo <gary@...yguo.net>,
	Björn Roy Baron <bjorn3_gh@...tonmail.com>,
	Benno Lossin <lossin@...nel.org>,
	Andreas Hindborg <a.hindborg@...nel.org>,
	Alice Ryhl <aliceryhl@...gle.com>, Trevor Gross <tmgross@...ch.edu>,
	Danilo Krummrich <dakr@...nel.org>,	David Woodhouse <dwmw@...zon.co.uk>,
 Jens Axboe <axboe@...nel.dk>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	NeilBrown <neilb@...e.de>,	Caleb Sander Mateos <csander@...estorage.com>,
	Ryo Takakura <ryotkkr98@...il.com>,
	K Prateek Nayak <kprateek.nayak@....com>
Subject: Re: [RFC RESEND v10 03/14] irq & spin_lock: Add counted interrupt
 disabling/enabling

On Mon, Jun 16, 2025 at 01:54:47PM -0400, Joel Fernandes wrote:
[..]
> > > 
> > > Your SOB is placed wrong, should be below Boqun's. This way it gets
> > > lost.
> > > 
> > > Also, is there effort planned to fully remove the save/restore variant?
> > > As before, my main objection is adding variants with overlapping
> > > functionality while not cleaning up the pre-existing code.
> > > 
> > 
> > My plan is to map local_irq_disable() to local_interrupt_disable() and
> > keep local_irq_save() as it is. That is, local_irq_disable() is the
> > auto-pilot version and local_irq_save/restore() is the manual version.
> > The reason is that I can see more "creative" (i.e. unpaired) usage of
> > local_irq_save/restore(), and maybe someone would like to keep them.
> > Thoughts?
> 
> My thought is it is better to keep them separate at first, let
> local_interrupt_disable() stabilize with a few users, then convert the
> callers (possibly with deprecation warnings with checkpatch), and then remove
> the old API.
> 

No objection to doing it slowly ;-) My point was more about the plan is
to replace local_irq_disable() with local_interrupt_disable() other than
replacing local_irq_save() with local_interrupt_disable().
local_irq_save() will still be available for "power users" if they care
about precise control of irq disabling. But it's not necessary to be
done at the moment.

> That appears lowest risk and easier transition.
> 

Agreed. Thanks for looking into this.

Regards,
Boqun

> thanks,
> 
>  - Joel
>